The invention relates to a method for producing calcium chloride scales. It also refers to a use of the method in the washing of exhaust gases.
The washing of exhaust gases, which are required for the incineration of rubbish, yield diverse solid substances which must be disposed of or which may in part be recycled. One of these substances is calcium chloride CaCl.sub.2. The CaCl.sub.2 contained in a dilute aqueous solution only becomes disposable or recyclable through concentration of the solution. The CaCl.sub.2 is advantageously brought into a solid form, which is stable at environmental temperatures of 20 to 25.degree. C. A hot CaCl.sub.2 solution whose concentration amounts to 75.5% by weight solidifies on cooling to calcium chloride dihydrate CaCl.sub.2.2H.sub.2 O.
It is known that, in addition to CaCl.sub.2.2H.sub.2 O, crystalline calcium chloride hydrates with a greater proportion of water exist; namely CaCl.sub.2.4H.sub.2 O and CaCl.sub.2.6H.sub.2 O.
It should therefore be possible to obtain a solid product of CaCl.sub.2.4H.sub.2 O or CaCl.sub.2.6H.sub.2 O respectively from a solution with 60.6% CaCl.sub.2 by weight or even 50.7% by weight. For a saving in energy as well as savings in the complication and expense of the apparatus which is associated with the concentration process, it would be desirable to produce such a product with an increased proportion of water. However, as practice has shown when a water-rich solution cools down--with the use of, for example, a cooling roller--a soft product arises which does not consist completely of crystallised phases, but still contains liquid components.